The Forest Republican. [volume] (Tionesta, Pa.) 1869-1952, 1887-09-28
SCIENTIFIC AND INDUSTRIAL


The finest collection Of butterflies In
the world is said TO be that at the Johns
Hopkins University. The collector Of
It is Herman Strecker, day laborer, who
works at stone-cutting, and does his
hunting after specimens, as he must, at
night, after his days work is over.
What is termed flexible glass is use
ful product Just introduced. Paper Of
proper thickness is rendered transparent
by soaking in copal varnish, and when
dry is polished, rubbed with pumico
stone, and layer Of soluble glass is APP
piled and rubbed with salt. The surface
is as perfect as glass.
The largest dam in the world is to be
built across the upper end of the San
Nlateo canyon, about four miles west of
the village of San Mateo. The dam will
consist of a solid wall of concrete, from
hillside to hillside 1t will be zoo feet
long, 110 feet high, 17j feet thick at the
base, and 90 feet thick at the top. The
reservoir which will be formed by this
dam will have a capacity of $4,000, 900
gallons, and some time in the future will
be connected with the San Francisco
watershed by tunnel five miles long
Electric lanterns will, it is thought,
take the place, in course Of time, of tho
ordinary mining safety lamps. A porta-
bic electric lamp can now be made, pos
scssing the following features: Weight,
about three pounds; illuminating power,
five candles; size and shape, similar to
present lamps; duration of light ten
hours; cost of repairs, charges of bat
terry, and materials, cents for ten hours;
these facts showing that there is nothing
to prevent its adoption as a substitute for
the present lamps, and even for candles
in many mines where they are still in
use.
The problem of protection against
yellow fever by inoculation seems in q
fair way to solution by the Brazilian
DOCTOR Freire who has been seven years
at work on the subject. According to a
recent account, the number of persons
already inoculated is 6,524. There have
died from yellow fever in Rio de Jaueiro,
between January, 1885, and September,
1886, 1875 persons, of whom eight hao
been inoculated Gn 1884, the method
being then imperfect) This gives a
mortality of about per 1, 900 for the in
oculated, and one per cent. for the un-
inoculatcd.
RustleSs iron is being manufactured in
New York by new process which, it is
claimed, converts the surface of the metal
into magnetic oxide of iron. This is
done by subiecting it successively to the
action of highly heated air and carbonic
oxide gas from coal fires. The hot air
converts the metallic surface into red
oxide of iron, which is then reduced to
black or magnetic oxide by the gas.
This renders it rust-proof when exposed
to the air or to fresh or salt water. The
process can be applied with most satisfac-
tory results to water pipes and architec-
turdl work.
4 forgotten chemical product, brought
out by Dode more than twenty years ago,
is now preserved in a Paris museum. 1t
is transparent reflector, in which the
image of an object may be viewed as in a
mirror or through which the object
itself may be seen as through common
glass. 1t is simply piece of glass COW
cred with a thin layer of platinum. 1t
was prepared by combining mixture of
platinic chloride and essence Of lavender
and borate and oxide of lead, spreading
the whole on the glass with a fine brush,
and then baking in mutfle at low red
heat. This old discovery ought to serve
some useful purpose.
Prof. A. G. Bourne writes to Nature
regarding the sense of taste or smell in
ieeches While in India he picked up
with his fingers stone from the soft,
muddy bottom of a shallow, torpid
stream. Returning to the same spot
few minutes later, he noticed a number
of leeches swimming near the spot. On
the following day, suspecting that they
had "smeltn or tasted his hand in the
water, he first stirred the surface of the
mud with a stick, but no leeches APP
peared after the water was clear again
he washed his hands in the water with
out disturbing the mud, and very soon
number of leeches came up and swan
about. The soft mud in which they live
is about foot deep, and although the
disturbance of the surface mud with a
stick was not sufficient to bring them
out, the 'smell" or "taste" of his hands
seems to have spread down and extended
over an area of more than yard. Last
year in the hill country he had an oppor-
tunity of observing the very keen scent
of the land leeches, which will go to a
man or horse from the banks of either
side or even wide road.